O6-methylguanine-DNA methyltransferase in wild-type and ada mutants of Escherichia coli.
AUTOR(ES)
Mitra, S
RESUMO
O(6)-Methylguanine-DNA methyltransferase is induced in Escherichia coli during growth in low levels of N-methyl-N'-nitro-N-nitrosoguanidine. We have developed a sensitive assay for quantitating low levels of this activity with a synthetic DNA substrate containing 3H-labeled O(6)-methylguanine as the only modified base. Although both wild-type and adaptation-deficient (ada) mutants of E. coli contained low but comparable numbers (from 13 to 60) of the enzyme molecules per cell, adaptation treatment caused a significant increase of the enzyme in the wild type but not in the ada mutants, suggesting that the ada mutation is in a regulatory locus and not in the structural gene for the methyltransferase.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=221460Documentos Relacionados
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